Structural anomaly

A structural anomaly in subtilisin has functional consequences Transition-state stabilization in subtilisin is dissected by protein engineering Catalysis occurs without a catalytic triad Substrate molecules provide catalytic groups in substrate-assisted catalysis Conclusion Selected readings... 

Similar to PbSe, the controlled growth of lead telluride, PbTe, on (111) InP was demonstrated from aqueous, acidic solutions of Pb(II) and Cd(II) nitrate salts and tellurite, at room temperature [13]. The poor epitaxy observed, due to the presence of polycrystalline material, was attributed to the existence of a large lattice mismatch between PbTe and InP (9%) compared to the PbSe/InP system (4.4%). The characterization techniques revealed the absence of planar defects in the PbTe structure, like stacking faults or microtwins, in contrast to II-VI chalcogenides like CdSe. This was related to electronic and structural anomalies. 

Exposure to the fetus in the first 2 weeks after conception may have an all or nothing effect (i.e., could destroy the embryo or have no ill effect). Exposure during the period of organogenesis (18 to 60 days postconception) may result in structural anomalies (e.g., methotrexate, cyclophosphamide, diethylstilbestrol, lithium, retinoids, thalidomide, certain antiepileptic drugs, and coumarin derivative). 

The conditions on the phase diagram for which this anomalous behavior occurs has been termed water s structurally anomalous region. Inspection of the order map (Figure 4) reveals a dome of structural anomalies within the temperature-density plane, bounded by loci of maximum tetrahedral order (at low densities) and minimum translational order (at high densities) as shown in Figure 5. Also marked on Figure 5 are regions of diffusive anomalies,... 

Htc-552 when expressed in E. coll undergoes spontaneous cytoplasmatic maturation (covalent haem attachment), in contrast to the usual periplasmatic maturation route for bacteria. NMR spectroscopy together with other techniques were employed to characterize Htc-552 expressed in the cytoplasm and periplasm of E. coli. It was shown that the cytoplasmatic product exhibits lower thermostability (r i = 85°C compared to the periplasmatic Tm = 90°C) because of structural anomalies in the region of the N-terminal helix, due to the retention of the N-terminal methionine and not to haem attachment errors. 

Thus, 2-furfuryl vinyl ether 6a is extremely sensitive to cationic activation (16) because of its very pronounced nucleophilic character, but the polymerization is accompanied by some gel formation due to abundant alkylation of the furan rings pendant to the macromolecules. This structural anomaly is not encountered with the 5-methylated monomer 6b (16) precisely because electrophilic substitutions take place predominantly at C5 and are therefore impossible with this monomer. A similar difference of phenomenolo was observed with the 2-fiiryl oxiranes 4a and 4b (17). 

Formal human studies are limited and based on naturalistic exposure with an attempt to have a control group matched as closely as possible. However, there are inevitably differences in such groups, the most obvious and perhaps most important being the reason why one group is on a medication while the other is not. In other words, the illness that led to treatment with the medication (in this case a mood disorder) may itself be a risk factor for lower fetal viability, increased incidence of perinatal complications, or congenital malformations including neurodevelopmental problems, as well as major structural anomalies (e.g., cleft palate, spina bifida). 

Most of the studies that have been done with antidepressants are limited to TCAs and SSRIs, most likely reflecting the fact that these medications are widely used (511, 512). The good news is that these studies have not detected an obvious increased risk of major structural anomalies. The cautionary note is that most of these studies assess the child immediately after birth and thus are insensitive to detecting neurodevelopmental problems that may only emerge after longer periods of time (e.g., learning or behavioral problems). 

The results of research on the NMR spectra of elements with different isotopic composition have been reported. (95) The particular interest of these investigations lies in the possibility of applying perturbation theory to account for the contribution of vibrational states to the shielding of nuclei. (96, 97) In addition, the measurement of nuclear g factors of isotopic pairs, with great accuracy, is required for evaluating small hyperfine structure anomalies. (39,98)... 

Y. Du, J. Fang, M. Zhang, J. Hong, Z. Yin, Q. Zhang, Phase character and structural anomaly of Bi4Ti30i2 nanoparticles prepared by chemical coprecipitation, Mater. Lett. 57 (2002) 802—806. 

Question When might structural anomalies occur ... 

This question is related to the problem of structural anomalies. 

Litt, M. PoIy(4-methyl Pentene) X-ray measurement of crystalline density and observation of structural anomaly. T. Polymer Sci. A1, 2219—2224 (1963). 

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